In recordable optical recording media, which have a recording layer containing an organic dye, and in which a light transmission layer is formed by coating of a photocurable resin, typically, firstly a layer, in contact with the recording layer, made of a photocurable resin having low elastic modulus of less than 40 MPa at 25° C. is formed; then on the layer of the photocurable resin having low elastic modulus, a layer made of a photocurable resin having high elastic modulus of 40 MPa or more at 25° C. is formed; so that the light transmission layer is formed such that the total thickness of the two photo-curable resin layers is 0.1 mm.
By forming the light transmission layer in such a way, deformations of the recording layer during the recording of the data, to be caused by that the laser beam is irradiated and the organic dye generates heat and decomposes to form a recording mark, can be absorbed and accepted by the layer made of the photocurable resin having low elastic modulus. It is thus able to realize sufficiently high modulation degree. Meanwhile, with the layer made of the photocurable resin having high elastic modulus disposed at the surface of the optical recording medium, it is able to prevent the optical recording medium from scratching.
However, in cases where the light transmission layer is made up of the layer made of the photocurable resin having low elastic modulus and the layer made of the photocurable resin having high elastic modulus in this way, there has been a problem that the optical recording medium is made with many layers and the production cost of the optical recording medium becomes high.
In view of this, by forming the recording layer with the use of an organic dye made of a metal complex compound formed by that an azo compound having a triazole structure is coordinated to a metal ion selected from the group consisting of nickel, cobalt and copper; an optical recording medium made up of only a photocurable resin formed by the photocurable resin having high elastic modulus of 40 MPa or more at 25° C., which has sufficiently high modulation degree and good recording characteristics, without including the photocurable resin having low elastic modulus of less than 40 MPa at 25° C., has been proposed.    Patent Document 1: Japanese Patent Application Laid-open No. 2010-33667